Blogger: How to Change Blogpost Line Height

I was googling for this yesterday, and despite of finding some blogs and help tutorials, they aren't very update with the current Blogger customization steps.

Most advices is to:

1. Go to Dashboard > Design > Edit HTML.
2. Find some line with post-body then line-height. It suppose to look something like this:

.post-body {
  line-height: 2;
}

3. Change the number to whatever line height you desire.
4. Save the template.
5. Check with your post/refresh your blog to see if it goes right.

BUT none of the tutorials I read mentioned about how to find that specified "post-body" line